From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 09138C61DA4 for ; Wed, 15 Mar 2023 06:50:34 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.509906.786624 (Exim 4.92) (envelope-from ) id 1pcKxb-0002LJ-0o; Wed, 15 Mar 2023 06:50:07 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 509906.786624; Wed, 15 Mar 2023 06:50:06 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1pcKxa-0002Ke-ST; Wed, 15 Mar 2023 06:50:06 +0000 Received: by outflank-mailman (input) for mailman id 509906; Wed, 15 Mar 2023 06:50:05 +0000 Received: from se1-gles-sth1-in.inumbo.com ([159.253.27.254] helo=se1-gles-sth1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1pcKxZ-0001yy-6h for xen-devel@lists.xenproject.org; Wed, 15 Mar 2023 06:50:05 +0000 Received: from EUR02-AM0-obe.outbound.protection.outlook.com (mail-am0eur02on2062a.outbound.protection.outlook.com [2a01:111:f400:fe13::62a]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id 9b313796-c2fd-11ed-87f5-c1b5be75604c; Wed, 15 Mar 2023 07:50:03 +0100 (CET) Received: from VE1PR04MB6560.eurprd04.prod.outlook.com (2603:10a6:803:122::25) by DBAPR04MB7445.eurprd04.prod.outlook.com (2603:10a6:10:1a7::22) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.6178.29; Wed, 15 Mar 2023 06:49:58 +0000 Received: from VE1PR04MB6560.eurprd04.prod.outlook.com ([fe80::154e:166d:ec25:531b]) by VE1PR04MB6560.eurprd04.prod.outlook.com ([fe80::154e:166d:ec25:531b%5]) with mapi id 15.20.6178.026; Wed, 15 Mar 2023 06:49:58 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 9b313796-c2fd-11ed-87f5-c1b5be75604c ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=TtnsFPvRI+ZCQTi6LDD1S9e0ihawTzV3SkGeWaXLE09RhbU4u1yw84di+bAAk8gy5ju0SbJuulFX4UeRYoEP480kmhyH7J7ClO/j9MT2Xs+CWbuKyawAhO5Ly7GDFU5+hVlEEEgSwDZDrq52vmzGaIY7nn7X3eXO/gboSL8HpZLLqD3DmXUlfaScuSrJUv6zsivuqArig/NymP0oKHD+4cFsAsWzyu8AIIgsjLG6rIE0w78G/8FOeR9IX+3Wh5zlIiIne6ENG11V+CZRyRfmMJkN7JD0emcF3e1e6bVqApvJCidDiW9HSPxLepnijj4XoY3yzpuNrP5g29Gg6Zvf/g== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=jzbVl/yx5DrEE6/AjikLXbhVVWbYOKgadlMTX5tIky0=; b=ksFv/4W6hERb6StSGK7bjp+4ECt4bhwxLvPegIouq6JVrQcjpmE20Zd0SKHMUkyc9/4IMcvkxOj6SK5N+xIxmoC02jnhhW1LYf1YYgkV+eZirTsahTz2UfIosCln5ssYvyKn9xZQ8/W1AORqzFP+OhtcnUfgr1YWiT/2SQQ7Rrk5AERetAziwS43UVucMsjdIB1VjP7uIq+qf/SJpCq+NA9t89X7tVAq58NVxX/dFUk3NvDg+b7kEIJoyqPfh4tNJFNEAr1q3vvJs35Dt/aWjbQd/lKXk8ShF1GmC2XMWJcfiue9IHcdWIN/1tAF7GLBHMzrBQwWfKgdKncdgyzZNw== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=suse.com; dmarc=pass action=none header.from=suse.com; dkim=pass header.d=suse.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=jzbVl/yx5DrEE6/AjikLXbhVVWbYOKgadlMTX5tIky0=; b=LY6XifRS1dF1S/xHyDHLsrcgUEe0OV8C9+jnJq7jRDQAKgVd/a/Tyc0tZXDzH+hkwIaXUgWGrNJT2SR5sMT2rCT7JflEZE3YVtBipOCsENYMpao27U9Zy1Wn581OkW4HolIFc+KGxu1pduoHcwyFayNazQDKNxYi/wF0sI6OFwjQrhyBlUv7zso1ZsEg1q8jPObMY9zF5apLWxX1cKnnwDLkgg8fzsoMy6AsLxVbEm3VKCwVAVa4KfkkAPuEg/OtM/WIIN17xKU0u7soIv9Zmi6WSFcAHPATWJrscdjuo2tLhbHhb8TKidyQX/12wvJKoposUPqXLXiLBr3gH3fE6A== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=suse.com; Message-ID: Date: Wed, 15 Mar 2023 07:49:55 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [RFC PATCH 1/5] x86/xen: disable swiotlb for xen pvh Content-Language: en-US To: Stefano Stabellini Cc: Huang Rui , Alex Deucher , =?UTF-8?Q?Christian_K=c3=b6nig?= , Stewart Hildebrand , Xenia Ragiadakou , Honglei Huang , Julia Zhang , Chen Jiqian , Juergen Gross , Oleksandr Tyshchenko , Boris Ostrovsky , =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org References: <20230312120157.452859-1-ray.huang@amd.com> <20230312120157.452859-2-ray.huang@amd.com> From: Jan Beulich In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ClientProxiedBy: FR0P281CA0139.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:96::14) To VE1PR04MB6560.eurprd04.prod.outlook.com (2603:10a6:803:122::25) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: VE1PR04MB6560:EE_|DBAPR04MB7445:EE_ X-MS-Office365-Filtering-Correlation-Id: 06617256-5f83-46a7-42fd-08db25217d90 X-LD-Processed: f7a17af6-1c5c-4a36-aa8b-f5be247aa4ba,ExtFwd X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:VE1PR04MB6560.eurprd04.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230025)(396003)(376002)(346002)(366004)(39850400004)(136003)(451199018)(36756003)(7416002)(5660300002)(83380400001)(478600001)(6666004)(6486002)(6506007)(26005)(53546011)(6512007)(2616005)(186003)(66476007)(66556008)(66946007)(8676002)(6916009)(41300700001)(4326008)(8936002)(31696002)(86362001)(54906003)(316002)(38100700002)(2906002)(31686004)(43740500002)(45980500001);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?MjN5ZDhJY0huRTNMeGxNbEV0anM4RitmUnNTc1hDajJMc0plZklDT1pUQWNR?= =?utf-8?B?cldvWlJqS3lLZ3JHdnhva2g4NEFPQjhZdURqVXM3Q1k2YW5PWS9YbGxOUzRt?= =?utf-8?B?OUxIdmpFaFQ4bEdwaVRQSTZqTUhGaEo0WW9sRzRnOTUwYkx1VlR3K2dTVWwr?= =?utf-8?B?YzNrVkd5OTcvMCtJRzBCckJENnpMS1NsMWo0UmZIL202NkMrQkl6V2lRb0Vj?= =?utf-8?B?ZXBFdFZETE05Yk43MTVEWStpc0tNS0tGOXgxRUVJQXpMSEt0eXFnUDhJVGRp?= =?utf-8?B?ZE0zYUliUzJSMEUzMk5UZHpTOE10dEhLR0l4YVJWTzBmNTBNY2NkcklMT0Ns?= =?utf-8?B?VVA5TEhmM3RKditYS3hPalJ5UC9tcDBTVFNGVkVPVzhZSzZLWVFOZVA1OWFC?= =?utf-8?B?L2ZDN1RkOXZ2K3NkRWdPeEVYWnAzUlJuSkVmQjdtNG1wSUlXeStsRGdTTkxj?= =?utf-8?B?OTBTSmU3VjJzRWdrTnZza0VORE1Zd0h6VzNiQkc4NW1ocW4xbVFWQk9leUNq?= =?utf-8?B?OXF6ejJGQW9kdUdnNGM2SjcwVzdzQkFHOCt6dm9JMnlFTG1PUzdxMzJ4SlF6?= =?utf-8?B?Tzl1NjAxckk2cDl1ZGd5VmpnVWM0SjRuUkZrc0s0TVhkelhFN3hBN1UxZWpV?= =?utf-8?B?RVVvN1V4ZzM3Rk5jczBLMTk1cXlXMWpQNEdOQlEwSVlObnc2MXNNMEhwRzVh?= =?utf-8?B?WEp4d3RDMVo2QXBlMkV0Ui96SWJwbjFTZTdnelhVOFQzUlF1VEFEZVdiMy9j?= =?utf-8?B?cm52czllN3M4amErck1MN2VOb09GNDhOVjh1anhTVnEzYXRibExUT05ZYkNP?= =?utf-8?B?UlhLQzBNcUoxNGFnU0xCZjRiNjlQVjVhWlBnTW9JNWhTMGFHdGY3U2hDWkx5?= =?utf-8?B?RTBnSXVmYXhRRGNzTEF3RlBYVU9WVmZBN1E1bjRTdG1DQmJXL0ZVNEdXS1hP?= =?utf-8?B?WTJ3SE5pREdGYWNpQllHT2hvSE5QZTNvM01UOHcySWNpcTVRMzZNVmRhVDlG?= =?utf-8?B?SlRBTW5PbGxvZ3F2cXZ0QVdObmY0dDZJa0E0cHVjeFh5enhqY254VFF3THF3?= =?utf-8?B?WkY1Y2tzTjRjQzR3UDRlUXIzc0hoNS9ua2UyZFZrNzRBNFM5Qk8yZ2VwRGFB?= =?utf-8?B?V1UxcENQNkdYbmJrRlozMHpnOXdrTXRWYVJNQk9JYUlkWlo4Q2RMTFgvOFFE?= =?utf-8?B?dmNzV2M5YTc2aC9GMWJQNVl5dDl0UmV4VklNc3R4VlNXYW15Mkd0ZGc3WExD?= =?utf-8?B?VDBEMms0WmpNVXczRlFJNnFLNjhBQVhtRVNrTGJ4RlRKOUNObG05WDdkeHBB?= =?utf-8?B?b28yV2pMck00WG9Dcms3Mzh5ck5VUmhPWS9PUWtaTVczS2oybUpidnh6U29E?= =?utf-8?B?bnAySlNxTkRBYVpBZHdpZ2U1M2JteWJRVTgyN2JoL0hVcmdWK08zMDYwVEF1?= =?utf-8?B?RGdESnErM0s0VDgxWXkxa0I3TkJCNzZrN3JvaFo3T3NZZ3NsQnJCZkFnSVlm?= =?utf-8?B?d1FWWUx3RXBZZ0FMaGRhQkF6UDN5dFJ1RVpPOU9lKzZsN3F0WTAybWI2SGVO?= =?utf-8?B?YlF6UldYN2laNTlUVU1iOW8xV2ZhTThPczNLNk01VU1KRnJERnk5Uk0yYnU1?= =?utf-8?B?YnQ3NlFQbHNZS0lpTGxpcWh1WFhUNVZUZTNta0lkZENzd2JKa0NKWTJwL1Jh?= =?utf-8?B?QktvQ3lKN2o3MVNVMzU1UVFZM2hwLzdxbzd5OGxyMG41ek1lQ2NYMW8rMldN?= =?utf-8?B?WjJQcXdrcmE3d0w1NDc3aElOeXBCVGYwQU42cjVUd3RoZ25HS2FQNE4yZkEz?= =?utf-8?B?dlZMajZQNXlWT2xmaC9rQUY1VlpydFJCT1kwdTcxcWx3anFud3dxNXQ0RFE5?= =?utf-8?B?VHVPSDUvbS9wcHNteGlsbVA0cTc1ayt2dTVSa1BGeVVHaXhUTGdWbXJEK3Y1?= =?utf-8?B?Z0I0cy9uK2NoaXBEdk5pN0t2ZTJyQm1weHVJU1IwczZIeE1YT2U2TUJoMGNa?= =?utf-8?B?cXBVbEQ2RXdlOXR6YzhSbmlmV2Q2KzhRWFZLdjN6V0VsYk1VRVhNVUUwN1ls?= =?utf-8?B?Z0grMTJzS0IzTTBEUGJWcmVJcE1VcUFFakllZHhuSFhEcm1DTlhHU0N4RElS?= =?utf-8?Q?RDC+kEvfm5GlxIdh/6CyiglsP?= X-OriginatorOrg: suse.com X-MS-Exchange-CrossTenant-Network-Message-Id: 06617256-5f83-46a7-42fd-08db25217d90 X-MS-Exchange-CrossTenant-AuthSource: VE1PR04MB6560.eurprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Mar 2023 06:49:57.6936 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: f7a17af6-1c5c-4a36-aa8b-f5be247aa4ba X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: DnfelH2g0m+8jfsfZsnfdbaZEgAoSmTBn/mC+WznUvdWV9/BZovw7KTH+VGGL9SHdRx3YaWN8k/3I+gatVbDfg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DBAPR04MB7445 On 15.03.2023 01:52, Stefano Stabellini wrote: > On Mon, 13 Mar 2023, Jan Beulich wrote: >> On 12.03.2023 13:01, Huang Rui wrote: >>> Xen PVH is the paravirtualized mode and takes advantage of hardware >>> virtualization support when possible. It will using the hardware IOMMU >>> support instead of xen-swiotlb, so disable swiotlb if current domain is >>> Xen PVH. >> >> But the kernel has no way (yet) to drive the IOMMU, so how can it get >> away without resorting to swiotlb in certain cases (like I/O to an >> address-restricted device)? > > I think Ray meant that, thanks to the IOMMU setup by Xen, there is no > need for swiotlb-xen in Dom0. Address translations are done by the IOMMU > so we can use guest physical addresses instead of machine addresses for > DMA. This is a similar case to Dom0 on ARM when the IOMMU is available > (see include/xen/arm/swiotlb-xen.h:xen_swiotlb_detect, the corresponding > case is XENFEAT_not_direct_mapped). But how does Xen using an IOMMU help with, as said, address-restricted devices? They may still need e.g. a 32-bit address to be programmed in, and if the kernel has memory beyond the 4G boundary not all I/O buffers may fulfill this requirement. Jan